1. Field of the Invention
The present invention relates generally to the field of equipment hoists used to vertically move various heavy vehicle components during maintenance or repair. Particularly, the present invention relates to a portable hoist, which may be positioned into a narrow workspace.
2. Description of the Prior Art
Portable hoists are conventionally used to lift and lower automobile components in the automotive repair and maintenance industry, for example transmissions, engine blocks, automobile rear ends and the like. Conventional portable hoists generally consist of a transverse beam, an upright member and a mechanical lifting device carried by some type of base. Typically, to hoist an engine, the base of the portable hoist is rolled under the automobile, the vertical mast is outside of the vehicle and against or near the outside panels of the vehicle and the hoist is positioned such that the transverse beam and lifting mechanism is over the center of the engine to be hoisted.
Establishments or shops where large vehicles, such as dump trucks, tractor trailers and the like, are serviced often need to raise, or support, heavy or bulky components (not requiring a full transmission lift) located within the engine compartment or underneath the truck, such as a steering box or portions of the transmission. Currently available lifts and hoists are too large and bulky to perform such tasks and require the user in two different physical locations, one to position the hoist and another to attach the hoist to the item to be hoisted. For the smaller, yet heavy and bulky components, the mechanic must physically hold the component by himself or with the help of another mechanic.
While well known conventional portable hoists generally have the same three main components, the configuration and geometry vary in several ways. First, the bases are of several types. Some are shaped like a xe2x80x9cVxe2x80x9d or xe2x80x9cH,xe2x80x9d and others as squares and rectangles while others still are telescoping or otherwise adjustable. Second, the hoists have upright members, which may or may not be adjustable. Third, the hoists have transverse beams that are either cantilevered, or supported on each end by the base. Lastly, like the upright member, the hoists with transverse beams may or may not be telescoping or otherwise adjustable. Regardless of the configuration, however, conventional hoists are generally supported by wheels, which provide the hoist with mobility.
Although various types of portable equipment hoists have been developed for lifting heavy automotive components, they have not been altogether satisfactory for use under large vehicles for components of intermediate size such as steering boxes or portions of a transmission.
U.S. Pat. No. 5,375,963 discloses a portable hoist with a rectangular shaped base from which a non-adjustable vertical mast upwardly extends. Pivotally connected to the mast is a telescoping transverse beam to which a linearly movable shackle bracket is secured. The transverse beam is moved vertically by a lifting ram pivotally connected to the mast end of the transverse beam and secured to the mast. There are several disadvantages to using this hoist in large vehicle maintenance. For example, the movable shackle and transverse beam must be coordinated together in order to position the rigging over the center of the component to be lifted. When working underneath a large vehicle there is no space to perform such adjustments. Additionally, when the rigging is attached to the shackle bracket it is done so at an acute angle, thus, making it impossible to lift the component out of the automobile in a true vertical plane. This requires extra care and unnecessary manual movement and guidance of the heavy component to ensure that it does not collide with, or otherwise damage, any other components of the automobile.
U.S. Pat. No. 6,164,625 discloses a portable xe2x80x9cVxe2x80x9d base hoist that is manufactured in such a way, and containing so many components, that it can be easily disassembled by one person. While this may be useful, it undoubtedly increases the cost, and simplicity, of a portable hoist. This device operates in much the same manner as the above prior art and has the same disadvantage of lifting the heavy component on an angle.
U.S. Pat. No. 4,118,010 discloses another portable hoist that is manufactured with several adjustable and removable components and also lifts heavy components on an angle.
U.S. Pat. No. 5,934,490 discloses a variably oriented xe2x80x9cHxe2x80x9d shaped multi hinged base from which an adjustable, vertical, column extends. A removable, adjustable, cantilever boom is pivotally attached to the vertical column along which a wire rope is run. The wire rope is connected at one end to a winch, located on the vertical column, and on the other end to lifting rigging located at the distal end of the removable boom. While this device lifts the automobile component in a true vertical plane, it is comprised of a large number of parts, thus, making it expensive to manufacture as well. Additionally, the xe2x80x9cHxe2x80x9d shaped base of this device occupies valuable floor and technician workspace when in use and is cumbersome to maneuver.
While these known devices may be suitable for their intended use, none can be installed and operated underneath a vehicle within small, accessible spaces while being easy to maneuver when in use and both simple to manufacture and use. The present invention fulfills a long felt need for a compact, portable hoist having the capability to be positioned underneath the truck within the engine compartment or along the drive train of the truck to vertically lift and lower, or support, heavy or bulky intermediate-sized vehicle components in a true vertical plane during maintenance or repair, and to be adjustable by the user while in a reclined position under the vehicle.
Therefore, what is needed is a portable hoist that employs a mechanical lifting device for lifting heavy or bulky vehicle components. What is further needed is a portable engine hoist that ensures the component will be lifted vertically. What is still further needed is a portable hoist that is simple and can be easily and efficiently manufactured. Yet what is also needed is a portable hoist that uses the advantages of the prior art but overcomes the disadvantages normally associated with their use for example, fitting underneath a truck within small spaces that are too small for conventional hoists. What is also further needed is a portable hoist that allows the user to adjust the position and height of the hoist as well as operating the lifting mechanism while the user is at the location of the component to be hoisted, and/or in a reclined position under the vehicle.
It is the object of the present invention to provide an improved portable hoist that can lift heavy or bulky vehicle components vertically from above the component. It is another object of the present invention to provide a portable hoist that is simple and can be easily and efficiently manufactured. It is still another object of the present invention to provide a portable hoist for lifting vehicle components that fits underneath a truck into spaces that are too small for conventional hoists. It is yet another object of the present invention to provide a portable hoist that allows a user to adjust the position and height of the hoist as well as to operate the lifting mechanism while the user is at the location of the component to be lifted such as in a reclined position.
The present invention achieves these and other objects by providing a portable hoist having a U-shaped base, a tail assembly having at least a tail leg attached to the base, a telescoping vertical mast extending from the U-shaped base, a cantilevered lifting beam attached to the top of the vertical mast, and a mechanical lifting system having a winching mechanism with a lifting cable attached adjacent to the back of the lower portion of the vertical mast near the base where the lifting cable of the lifting system passes across the cantilevered beam from the back of the portable hoist to the front of the portable hoist. Because of its U-shaped base and relatively compact design, the hoist is nimble and easily positioned underneath trucks and within tight spaces where conventional hoists cannot be positioned.
The base of the present invention is provided with a transverse base member which has a pair of wheels attached to the bottom of the base member near each end. A pair of spaced base legs are connected to the front side of the base member. Wheels or other means for rolling support are attached to the bottom of the base legs at the end opposite the base support.
The tail assembly provides the hoist of the present invention with stability when in use by providing a counter moment to the turning moment transmitted through the cantilevered lifting beam and vertical mast. The tail assembly may also provide a mast coupler for mounting the vertical mast to the base and for securing the lifting mechanism to the hoist. The tail assembly may also include a tail plate having a top side, a bottom side, a front and a back, a tail tube (also called the mast coupler) secured to the top side, a tail wing mounted vertically to the top side of the tail plate and abutting the tail tube at approximately its center, and a tail leg secured to the bottom side of the tail plate near the back of the tail plate. The tail leg projects in a downwardly, angled position terminating with a wheel or other rolling support. The tail wing has an aperture for securing the bottom end of the winching mechanism. The tail assembly is secured to the top surface of the base support.
The telescoping mast includes lower mast, a middle mast and an upper mast. The tail end of the lower mast is inserted into the tail tube of the tail assembly. Because the mast is adjustable, the hoist can be used to hoist components on a truck while the truck is either on the shop floor or raised on a lift, jack or ramp. The middle mast is telescopically received within the lower mast and the upper mast is telescopically received within the middle mast. The lower mast has one through hole near its top end. The middle and upper mast sections have a plurality of through holes, which are similar in size and location. Removable pins, bolts, rods, and the like sized to fit the holes in the mast components allows for vertical height adjustment of the mast. The lower mast has one through hole and a lifting device hold down element. The hold down element is affixed to the back of the lower mast and is used for holding the upper end of the winch of the mechanical lifting system.
The cantilevered lifting beam having a front end and a back end is horizontally attached to the top of the upper mast nearer its back end than its front end and includes a roller or rotatable wheel at each end of the beam. The rollers rotatably support the lifting cable of the lifting system. The beam is braced by an angular brace member between the lifting beam and the upper mast. The cantilevered lifting beam provides the means for supporting the weight of the component when the hoist is in use.
The mechanical lifting system provides the present invention with the mechanical advantage for hoisting the heavy or bulky component. The lifting device of the lifting system is located on the back side of the hoist, i.e. the opposite side of the hoist from which the base legs protrude. The lifting device is located between the hold down element and the aperture of the tail wing such that the user can easily operate the winching mechanism when both the hoist and technician are underneath the truck. The lifting device may also swivel about its hold down connections providing the user the ability to make height adjustments to the hoisted component without having to move around to the location of the winching mechanism.
The lifting system also includes the lifting cable that is preferably a wire rope, which is run upward along the mast, threaded though the lifting beam, run across the rollers and extended downward from the lifting beam. A lifting shackle is secured to the free end of the lifting cable.
When an operator desires to hoist a heavy or bulky component the invention is rolled underneath the truck. The nimbleness of the U-shaped base allows the cantilevered lifting beam and lifting shackle to be positioned directly over the center of the vehicle component to be lifted. The vertical mast is then adjusted, if needed, by telescoping the middle and upper mast sections to the desired height, aligning a pair of through holes located in each of the mast sections then inserting a bolt, cotter pin or the like, through the aligned holes. Next, the lifting system is operated by attaching the lifting cable and securing the lifting shackle directly or indirectly to the component. The handle of the winch is then operated to tighten the lifting cable sufficiently to support the vehicle component. The component will lift in a true vertical plane. No further adjustment or movement of the hoist, or component, is needed. If desired, the hoist with the component attached may be removed to some remote location.
When an operator desires to install a heavy or bulky component the vertical mast is adjusted, if needed, to the appropriate height as described above and the component is secured to the lifting shackle. The invention is then rolled into position under the truck where the component is to be installed. Next, the mechanical winch is operated to lower the component into the desired spot with no further adjustment or movement of the hoist. Once the component is installed in place, the lifting shackle is disengaged and the hoist can be removed from underneath the truck.
Due to its configuration, the hoist of the present invention is stable when hoisting or supporting a load. At no time does the user/technician need to worry that the hoist base wheels will become airborne or that the load will shift or otherwise cause the hoist to fall over. The present-invention also uses a minimum number of parts. Further, the present invention is still more of an improvement because it can be easily positioned under a truck. An additional improvement is that its mechanical operation and configuration makes the present invention nimble enough to reach vehicle components, yet occupies a relatively small amount of space when in use and does not require the connection of electric or pneumatic power to operate.